清洁压裂液在煤层气井压裂中的应用

APPLICATION OF CLEAN FRACTURING FLUID IN COALBED GAS WELL FRACTURING

清洁压裂液自1997年首次被斯伦贝谢公司研制出以来,已经在国内外油气井的压裂改造中取得了良好的效果。由于清洁压裂液易于彻底破胶、流变性好、携砂能力强,可以提高压裂规模且对地层伤害较小,中联煤层气有限责任公司在陕西省韩城地区选用清洁压裂液对煤层进行了压裂试验,共压裂3口井、8层煤层,施工成功率100%,并取得了良好的压裂效果,压完后的火把高度2~4m,平均砂比均在30%以上,最高单层加砂68m3,压后放喷液显示完全破胶(未添加任何破胶剂),放喷初期黏度一般低于10mPa·s,放喷4h后黏度均低于5mPa·s。此次清洁压裂液成功应用于煤层压裂改造在国内外尚属首次,为大规模改造煤层同时尽量降低煤层伤害提供了一条新的途径,文章对清洁压裂液及煤层特点所做的室内研究情况及现场应用情况进行了详细的介绍。

Since clean fracturing fluid was developed and introduced by Schlumburger in 1997, it has achieved excellent track record in oil/gas well fracturing & simulation operation both in and outside China. Due to its gelout easiness, good rheology property and strong prop-carrying capacity, clean fracturing fluid is used for larger fracturing scale with less damage to the formation. Zhonglian Coalbed Gas Co., Ltd. conducted fracturing tests with clean fracturing fluid in Hancheng District of Shaanxi Province on three wells and eight coal beds with 100% success and excellent fracturing results. After fracturing, flare is 2-4 m high and average proppant concentration is above 30% and maximum single bed proppant addition is 68 m^3. Open flow fluid after fracturing showed complete gel-out (without adding gel breaking agent) and viscosity at early open flow phase usually was <10 mPa·s and that after 4h open flow was <5 mPa·s. The fracturing test was the first time both in and outside China that clean fracturing fluid had been used in coal bed simulation and revealed a new approach for large scale coal bed simulation with lest formation damage. This paper describes lab research and site application of clean fracturing fluid and coal bed in detail.